All-trans Retinoic Acid Release from Surfactant-free Nanoparticles of Poly(DL-lactide-co-glycolide)

In this study, we prepared all-trans retinoic acid (ATRA)-encapsulated, surfactant-free, PLGA nanoparticles. The nanoparticles were formed by nanoprecipitation process, after which the solvent was removed by solvent evaporation or dialysis method. When a nanoparticle was prepared by the nanoprecipitation solvent evaporation method, the nanoparticles were bigger than the nanoparticles of the nanoprecipitation dialysis method, despite the higher although loading efficiency. Nanoparticles from the nanoprecipitation dialysis method were smaller than 200 nm in diameter, while the loading efficiency was not significantly changed. Especially, nanoparticles prepared from DMAc, 1,4-dioxane, and DMF had a diameter of less than 100 nm. In the transmission electron microscopy (TEM) observations, all of the nanoparticles showed spherical shapes. The loading efficiency of ATRA was higher than 90 % (w/w) at all formulations with exception of THF. The drug content was increased with increasing drugfeeding amount while the loading efficiency was decreased. In the drug release study, an initial burst was observed for 2~6 days according to the variations of the formulation, after which the drug was continuously released over one month. Nanoparticles from the nanoprecipitation dialysis method showed faster drug release than those from the nanoprecipitation solvent evaporation method. The decreased drug release kinetics was observed at lower drug contents. In the tumor cell cytotoxicity test, ATRA-encapsulated, surfactant-free, PLGA nanoparticles exhibited similar cytotoxicity with that of ATRA itself.